Solid-state lighting technology such as light emitting diodes (LEDs) continue to increase in efficiency and capabilities, and have become a viable alternative to traditional incandescent and fluorescent light bulbs in many general lighting applications. For example, LED-based bulbs generally provide longer operational lifespans than traditional light bulbs, high-energy efficiency, compactness, and reliability.
One design challenge facing increased adoption of LED-based devices is their directional lighting characteristics. For instance, LED bulbs/devices generally deliver directional light, also known as forward light cone. A significant challenge for LED lighting (particularly retrofit LED A-type lamps) is to achieve wide light distribution. Non-limiting examples of LED modules or lamps include U.S. Pat. No. 9,068,701 (Progl); U.S. Pat. No. 8,449,150 (Allen); U.S. Pat. No. 8,297,799 (Chou); U.S. Pat. No. 8,287,147 (Tian); U.S. Pat. No. 8,226,266 (Chiang); U.S. Pat. No. 8,021,028 (Riesebosch); U.S. Pat. No. 7,160,012 (Hilscher); U.S. Pat. No. 7,011,430 (Chen); U.S. Pat. No. 6,899,443 (Rizkin); U.S. Pat. No. 6,746,885 (Cao); U.S. Pat. No. 6,227,679 (Zhang); U.S. Pat. No. 5,806,965 (Deese); U.S. Pat. No. 5,567,036 (Theobald); US Pub. 2014/0218931 (Desilva); US Pub. 2014/0153236 (Chen); US Pub. 2012/0032573 (Lai); US Pub. 2011/0095686 (Falicoff); EP 1 060 340 (Scianna); German DE 100 29 069 (Stoyan); and PCT WO 99/53234 (Schlag).
Most of the known LED retrofit A-type lamps cannot emit light having a generally uniform, omnidirectional distribution. Unfortunately, some of the known LED lamps do not fit within a spatial envelope defined for the particular lamp that is to be replaced (e.g., but not limited to, an ANSI A19 spatial envelope as generally illustrated in FIG. 1), and therefore cannot be considered to be retrofit LED lamps. Moreover, some of the known LED A-type lamps include complicated optical and secondary optics such as side-emitting LED packages, wherein a side-emitting LED package of this prior art is understood as an emission face for emitting light coupled to an optic/cover that is disposed directly adjacent to (e.g., on top of) the emission face that redirects the light such that a significant amount of the light emitted from the side emitting LED package is emitted substantially parallel to the emission face of the LED. Examples of a side-emitting LED arrangements is described in U.S. Pat. No. 7,192,155 (Morrow). Unfortunately, some LED lamps that utilize side-emitting LED packages cannot achieve generally uniform omnidirectional light distribution and/or the necessary optics reduce the overall efficiency of the LED type lamp and increase the manufacturing costs making them commercially impractical.
These and other features of the present embodiments will be understood better by reading the following detailed description, taken together with the figures herein described. The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing.